a natural force

The person thus described is being compared to a force of nature such as a typhoon or thunder and lightning.

You must look at the surrounding sentences to get your clue. Context is important.

Natural force of what? for econmic power? military power? social change? fashion influence?

So it simply means that someone is very strong or powerful and has a great deal of influence, just like a natural force. i guess that's all to it. thanks.